RFR: 8322768: Optimize non-subword vector compress and expand APIs for AVX2 target. [v2]

[Emanuel Peter]

On Fri, 5 Jan 2024 09:35:34 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Thanks for the comment addition!
>
> Improvement suggestion:
> For a vector with 8 ints, we get `2^8 = 256` many bit patterns for the mask. The table has a row for each `mask` value, consisting of 8 ints, which provide the valid permute index corresponding to set bit position in the `mask`, or a -1 (default) value.

@jatin-bhateja thanks for the update!

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PR Review Comment: https://git.openjdk.org/jdk/pull/17261#discussion_r1444256359